No they are not all the same.
You should read this thread, and search the archives to make a informed decision. As for pricing, shop around, I usually choose to purchase from Geno’s garage since they have great customer service, include all the extras and instructions you will need, are nice people.
https://www.turbodieselregister.com/forums/showthread.php?s=&threadid=53185
Personally I would choose Westach or Autometer. They are both made in the states and are quality units. I have a Autometer phantom EGT gauge mounted in a mopar A-pillar gauge pod. It is a very close match to stock, and looks like it is OEM. I would have chosen a Westach boost/EGT gauge, but at the time I was purchasing, the Westach combo gauge was backordered for weeks, so I went with the Autometer EGT gauge.
Really, they all seem like they are good, the only problems I have heard about are with the bezel in the Isspro gauges falling off inside the gauge in extreme heat, and some guys have complained about their X-Monitor, and some guys love them.
Pick what suits you and really take your time with the installation.
Peter